Beacon



May 5, 1942. E. R. PARSBERG BEACON Filed Oct. 17, 1938 4 Sheets-Sheet 1 I ATTORNEY.

y 4 E. R. PARSBERG' 2,282,208

BEACON Filed Oct. 17, 1938 4 Sheets-Sheet 2 a MNVENTZR y 1942- E. R. PARSBERG 2,282,208

BEACON Filed Oct. 17, 1958 4 Sheets-Sheet 3 6% W 1 VB TOR.

/ 4:. ATTORNEY.

May 5, 1942. E. R; PARSBERG BEACON Filed 001:. 17, 1938 4 Sheets-Sheet 4 Y I VENTOR.

Patented May 5, 1942 UNITED STATES AT EN F F1 6 E BEACON 4 Claims.

This application-is a continuation-impart of my copending application: Serial No. 170;046',' for Beacons; filed in the-Unitedstateson October'ZO; 1937, and in Sweden on- October 31, 1936, and relates back-thereto for-all common subject matter.

My' invention relates to aerial beacons, that is, to beacons for guiding aircraft.

One of the objects-of invention isto provide a beacon of this naturewhich indicates: to the pilot of the aircraft the"- direction of the proper flying route, and also makes it possiblefor the pilot to identify the particular beacon which he is observing. Another object of my. invention is to provide a beacon 'having the' foregoing characteristics and in which the beam of light emitted therefrom is projected above ahor'izontal plane during all, or at least a major portion of the time. i I

Heretofore, beacons have been provided in which the beam of light is caused to rotate'about a vertical axis, the beam either being projected in a substantially-horizontal direction, or inan upwardly inclined direction so as to describe a cone. beam is always at or above a-horizontal plane, and therefore visible to a*pilot, the beacon gives no indication as to direction; inasmuch as it rotates continuously through 360. Consequently,

a pilot approaching the'bea'con' has no way of determining his actual direction of flight. There have also been provided beacons in which the light sourcerotates continuously about a horizontal axis. While such a beacon enables a pilot to determine his direction of flight; providing he knows th orientation of that particular beacon, the beam emitted thereby is. directedinto the ground during: one' half the revolution and is therefore of no utility.

Further objects and advantages of my invention will be apparentfr'om-the followingdescription considered: with=the accompanying drawings which form part of. this specification and of which:

Fig. 1 illustrates diagrammatically a method of signaling'in accordance with oneembodiment of my invention;

Fig. 2 is a side view of anapparatu's for {producing signals-in accordance with" the method illustrated in Fig. 1;

Fig. 3 is a cro'ss se'ctional view taken on the line 33 of Fig.2;

Fig. 4 is a perspective viewof the light-source shown-inrigs. 2 and 3;

Witha beacon of this nature, while the Fig. 5 isa perspective view of modified' form of light source; 7

Fig. 6 illustrates diagrammaticallya m'etliod of signaling in accordance 'with 'another eatenment'of my invention:

Fig. 7 is an end View of an apparatus for emitting signals in accordance with them'e'thod illustrated in Fig. 6; I

Fig. 8 illustratesdiagrammatically a niethod of signaling in" accordance with athird embo'di ment of my in'ventionj Fig. 9 isan end-viewpl an-aparatus for producin'g" signals in accordancevvith 'themethod shown in Figit I Fig. 10 illustrates diagrammatically'astill fur ther method '01 pi'odiicing signals';

Fig. 11 Ba side View of an- -appa'ratus fOl"-pl.0 ducing the'signal's shown diagrammatically in Fig. 10;

Fig. 12 is a cross-sectional viewtaken on the line 12-42 of Fig; 11; I

Fig. 13 is a cross-sectional-view take'ii od-the' line l3-'-|3 of Fig. 11;

Fig. 14 illustrates diagrammatically another method of producingsignals: I

Fig. 15 is a side view of an apparatus forproducing signals shown in Fig. 14;

Fig. 16 is an endviewof the apparatus shown in Fig; 15;

Fig.1? is a cross-sectional view taken on the line H-ll of Fig. 15;

Fig. 18 is a side view of an apparatusfor pro ducing signals in accordance with afur-th er em bodinient of my invention; and

Fig. 19 is'aoross sectionalview-taken on'ithe line I9-|9 of Fig. 18.

Referring'more particularly to Fig. 1, reference character 10 designates generally light source adapted to be rotated about an axis II. As indicated by the arrows, the light source is rotated through so that the beam I2 emitted thereby passes froma horizontal position'fup Wardly to a vertical posiiton and thence downwardly to a horizontal position. Thefrotation of the light source is then reversed. Consequently, the beam is always directed along or above" a horizontal plane, and is never directed intothe ground. The beam is thus at alltimes' available as a beacon. Moreover, the axis H is arranged at right angles to the flying route at the point where the beacon is placed and thus the symmetric axis I3 of the beam sweepsbackand forth along the route and clearly indi'c'atesit's' direction toa pilot.

In g 2 an'clB there iss ivn an a paratus for producing the above described signals. Reference character l4 indicates a casing within which may be mounted any suitable source of power, such as an electric motor arranged to drive a cam disk l5 at constant speed. Disk I5 is provided with a cam track l6 of the shape shown in Fig. 3. A member I! is pivotally mounted on a. shaft I8 carried by a fixed arm I 9. One end of member I! is provided with a cam follower 20, while the other end is in the form of a segment 2| of a gear. The teeth of this segment mesh with a pinion 22 mounted on a shaft 23 which also carries a reflector 24. Mounted at or parallel to the axis of rotation of reflector 24 is an elongated light source, such as a tubular high pressure mercury lamp 2 5. An additional reflector 26 may be placed in front of the lamp so as to reflect the light which strikes it back against the main reflector 24. This arrangement of reflectors and elongated light source will emit a flat fan-shaped beam I2, as shown in Fig.1. The operation of the above described device is as follows: As cam disk l5 rotates at a constant speed in the direction of the arrow shown ineFig. 3, the cam track I 6 causes the follower to move toward and away from the center of rotation of the cam. This causes the member I l to rock back and forth on the shaft I 8 through a' certain angle. The gear ratio between gear segment 2| and pinion 22 is such that this rocking movement causes the pinion 22 and the shaft 23 to oscillate through 180. The reflector 24 is so arranged on the shaft 23 that the beam emitted thereby swings back and forth through 180?, Y

but always at or above a horizontal plane. Instead of the reflector arrangement illustrated in Fig. 4, a Fresnel type lens 21 may be employed with a reflector 28 and the elongated This reversing of the movement of the beam near the horizon is a characteristic of a particular beacon, thus enabling a pilot to identify the beacon and, knowing the location of this particular beacon, he is able to determine his own location.

The apparatus shown in Figs. 2 and 3 may be modified to produce the signals shown in Fig. 6 by substituting the cam disk'3ll shown in Fig. 7. The'cam track 3| is formed with reverse curves 32 and 23. That is, at the point where the track 3| is approaching the greatest distance from the center of rotation of the cam disk, the trackis caused to curve in slightly toward the center, as shown in 32, while at the point where the track is approaching closest to the center, it is caused-to curve out slightly therefrom. The above described device operates as follows: As the disk rotates in the direction of the arrow from the position shown in Fig. 7 the cam follower 20 is caused to move toward the left, thus rotating member I! in a clockwise direction. This movement continues until the reflector 24 has been rotated in a clockwise direction far enough to cause the beam emitted thereby to extend substantially horizontal. At this point, the first half of the portion 33 of the cam track causes the follower 20 to be moved in the track from the portion 33 to the portion 32, this part of the track being designed to rotate the member H in a counterclockwise direction through a sufficient angle to cause the re fiector 24 to rotate 180 in a clockwise direction. The portion 32 of the cam track acts similar to the portion'33, that is, it causes an oscillation 'of the reflector through the angle on, before the reflector is caused to turn back through 180.

.The signal as illustrated in Fig. 8 consists in rotating the beam through an angle equal to B, then reversing the beam through the angle 5, and then causing it to continue to rotate through an angle of 90+ e.' In other words, the beam rotates from the horizon to a little past the zenith, then turns back through a small angle, and then reverses and continues to the other horizon.

The cam arrangement suitable for producing such motion is shown in Fig. 9. The cam disk 35 is provided with a' track 36 having portions 31 and 38 which produce the oscillation of the beam through the angle 5 when the beam is near the zenith, in a manner similar to that de- .scribed in connection with Fig. 7.

In the signal diagrammatically shown in Fig. 10, the beam is caused to rotate about the axis l of the light source through whereupon rotation about this axis is interrupted, while the beam is caused to oscillate back and forth through 180 about the symmetric axis l3. An apparatus suitable for producing such a beam is shown in Figs. ll, 12 and 13. In this apparatus a shaft 40 is driven at a constant speed by means of any suitable motor in the housing 14. Shaft 40 carries a cam disk 4| having a cam track 42 on one side thereof and a cam track 43 on the other side thereof. Pivotally mounted on a fixed shaft 44 is a member 45, one end of which carries a cam follower 46 which cooperates with the cam track 42. The other end of member 45 is formed as a gear segment 41 which meshes with a pinion 48 mounted on a tubular shaft 49 carried in suitable bearings. The opposite end of tubular shaft 49 is enlarged to form a gear box 58 and provides a bearing 5| in which is mounted a shaft 52 to the outer end of which is rigidly secured reflector 24.

The inner end of shaft 52 carries a bevel gear 53 meshing with a similar gear 54 which is mounted on the end of a shaft 55, the shaft extending within and, beyond the tubular shaft 49. The opposite end of shaft '55 carries a pinion 56 which meshes with a gear segment 5! formed on a member 58 which is pivoted on a shaft 59.

The opposite end of member 58 carries follower 60 which cooperates with the cam track 43.

The above described apparatus operates as follows. It will be seen that rotation of the hollow shaft 49 causes the reflector 24 to rotate about 1 an axis coinciding with the center of the shaft,

cedes from the center of-' rotationiotflthe Seam-z Rotation: of theinner'shaffl55 -resuitfrom '-oscillatio'n: of the member 58' 'caused bsizthe coom eration of the. follower 6U -with? the cam": track 53. Camltracli 42 is fom1'ed withtwo' eoncentric ortions 6 i and 62 sothat, whi'le the follower' is withinthese concentric portions; no movement oi the' memberli re'siilt'si Likewise cam -"tra'ck 43 is tormedtw'o concentric. portions-w and 64; The concentric portionsaor thetwo: camsare so arranged: withr respect to each other that, when. the f0110We1 45- is in' ei-ther the concentric portion 6 I" or GL' the *follower fill' will bein an eccentric; portion-cof -the cam tracks 3% Likewise, wheni'th'e follower "60 is within ::the conceri tric portion 63-" or 64, th8'fo1lower 46. will'be in an. eccentric portion of the track 42'.- Hence, rotation of shafts 49 and 55 dwnotta'ke. place at thetsame:time; one shaft beingwheld: stationary whilethe other turns and.:vice 'ver'sai The above mechanism produces the signal shown insFig. 10, Asthe-beam' is caused taro tate through 180 aboutfthe axiszll by means of the member 451 rotating fthe' hollowfshaft fl; the. inner shaft" 55 is' held stationary, fas'x follower E is 'inixon'e of: the concentric ortions 63 Orof track-43$ When the-beamreaches a-substafi ti'ally horizontals aplane; the mellow-"shaft"?le -is heldistationaryf as "followi wis in oneor -the concentric "portions I: or." 62 "of" tracking while the inner shaft 55 is" rotated- "180" in? 'onez'direction andthen 180 in the reverse direction by the cooperation. of follower 60 with aneccentrl'c portion. of cam track 43 The above described movements of: the beam result in. different signalsr depending upon whether the pilot is flyingx alo'ngi 'the correct route, or' off to onemside of 12116 3311133 When following the route at approximatelyathe same elevation 'as the beacon andihence approaching the beacon al'o'ng'an extension of the symmetric axis W, the pilot will see thesignal brightly while the reflector is not rotating-.labout' the axis l I, that is while it is rotatingabout the:- axis 'ii. Due to the fact that beds in direct line with this axis, the rotation about the' axis: I3 will not i be apparent to him,-:as he will receivei'the"direct rays. of the light throughout the entirei periodxoi rotation. Consequently: he 1 will seexiflashes "of longduration spaced at-comparatively rlong zin' tervalalthe: intervals being the time required for the beam to: rotate about; the axis :1 Ir to-the opposite ihorizcn; osci llate iaboutrthe-axis 13,; and return to the a horizon: from whrohthe 4 shipibis approaching:

If the pilot is approaching the beacon at the same elevation" but from an anglewor fiying' 'parallel tothe route but a substantial:-distanceto either side thereofg'the; signal Willa-appear. to him as three' flashes, a "long interval threeifiashes; etc. This'is caused byithefact: that-, as the fanshaped beam comes down to-theihori'zor-r; the edge of the beam strikes=the pilot and giveshim one flash. Almost immediately;thrbeamzstarts to rotate about the axis-13, andtherpilot -is "no longer within the direct-rays of the edg'ei of the amass hel'ax The third hash: is 'receivedr lwhen ther first edge' oi the rbe'am ag'aim strikesrthe-aapilott 1 Heathusknowsthat hea off? itonion'e': side" "of the proper route; andmay: correct hisecours'e accordingly.

However;: it: the :pilot "flying -asubstantial distance boveithe planewofi the beam when the laitte'r a substantiallyihorizontal position, he observes: four: flashes; of which thec two middle onesrxwi'll be. of longer rdu rati'on; thecloser' ltd-the proper route the pilot is: flying; Moreover; the lowerr'rthe flyirlgc' height, the :shorter .is'fhthe inter"- valabetweenztheztwo middle-flashes: irxthe ship is ofitol onez side'oir the beacony orz between .theifir'st and seeoncl'wzfiasheszand': between; the: third and fourth? if the ship is": offtto the other side of'the beacon.

Theszfoun'fflashesiiare caused as follows; assuminghthat the; beam" rotates 'about the axis 13 first inea clockwise direction and then r in r a count terclockwise 'dirction; amt assuming it that the ship is above and 'to :the rightsofitheaxisr13 a 7 As the beam comes down toward the horizomi one edge thereofi passes the pilot and he observes one fla'shfwhi'ch is of: the same duration; regardless of the distance the' shipais above' or to 'theright ot the'axia the'beam' turns over around. the axis :I 3' he-- receives another flash: The" intervalbetweenr these 'two" flashes depends upon? hiscdistance -to-the rightz-and'above the axis. The furither he "iS TaJJGVG :theaxis; the 'shorter-twill be' the interva'lydue to the act that therbeam 7110- tates through an smaller: tangle ibeforer iti stmkes hirm': Likewise-the closer he 'islfto' the axis in a horizontal. direction; the smaller "will be this angl'e and hence' the shorterrthe interval"; Moreover; "the closer he is to: the axis; the: longer" will be the "duration of. the second? flash, inasmuch as the linear vel'ocityofrthe'beam is 'le'ss close to its axisof rotation' and' hence" it does not pass the pilot so rapidly. Th'ethird' flasnis received when the beam rotates back around the ax-is l3. The closer theship is" to; the ground, the shorter will :ber the interval betweenthe second and thirdfials'headueto the fact that the beam is requ-ired'toturn through a smaller angle Also the further" the shipfi's to:-the right of the axis, the shorterwill be -the intervalw forthe same reason. The duration of the-third flash for any iven position of-the ship: will bathe same as the duration'of the second'zflash," that is "the duration will be longenzthe closer the ship is to the axis 13. The fourth fiash is obtained when the 'h'eam again.rotatesrahout the axis ll back toward the: other) horizon; Fora given position of the ship, the interval: betweemtha third" and fourth flashes will be the-sameas =hetween-the first and secor.\cl.-..v

It the ship is tothe alettiof the axisiltl-the-du ration-of the various; fiashes will 'be the' same? as though the ship were' 'a similar dist'anceto. "the right of the axisbut the intervals: between the flashes-wi1lx be difii'ent: ThG'I'fiISlWflQSh 'is"re-" ceived whenr'thebeam; rotating about the axis H-, passes'the pilot on itswa-y'down to the horizon. The second bflaslr wilhbei received when the: beam rotates ina clockwise direction about the; axis l3.- Duato-then-fabt: that the beam rotates lessthan about "-the (axis 13, before strikingrthe ship -whenrtherlatter is to: theleft of I the axis, whereas the beam -must rotate more than'90" when the ship is totheright of the axis, the interval between the firstand second flashes will be shorter when the ship is to the left than when it is to the right. The, third flash is received when the beam rotates counterclockwise about the axis l3. The interval between the secondand third flashes is the time required for the beam to rotate about the axis l3 more than 90 until it reaches a horizontal position and then rotates back throughmorei than 90 until it again strikes the ship on'the' left side of the axis I3. This results in $9. comparatively long interval between the second and third flashes when the ship is to the left of the axis, whereas, as above explained,fthe interval between the second and thirdflashes is'short when the ship is to the right of the axis. The fourth flash is observed when the beam rotates back about the axis Hand the interval-between the third and fourth flashes is the same as between the first and second.

Thus, the pilot is able to determine, by observing the intervals between the flashes, and the duration of the second and third flash, how

far and to which side he is off the proper flying route, and thus is enabled to cordingly. I

It will be noted that the same beacon may appear to a pilot to emit different signals, depending on whether the pilot is approaching it at the elevation of the beacon, under which condition he receives three flashes, 'or approaching it at a'higher elevation, under which condition he receives four flashes. This would tend to conalter his course acfuse thepilot as to the identity of the beacon.

Consequently, if the beacon is-so located that it is possible for the pilot to" approach it at the same elevation, for instance if 'the beacon is on a'mountaintop, it is preferable to rotate the beam more than 180 around the axis 1 I so that the symmetric axis I3 is inclin'ed'downwardly during the time that the' beam rotates therearound. If this is done, the pilot'obtain's four flashes, even though he is flying in the same horizontal plane as that occupied by the beacon.

The signal illustrated in Fig. 14 consists in oscillating a beam back and forth from one hori zon to the other about the axis ll, while at the same time causing it to continuously oscillate rapidly through a small angle 6, about its symmetric axis 13. The apparatus shown in Figs. 15, 16 and 17, produces such'a signal. This apparatus consists of a cam'disk 10 provided with a cam track 1|, which is of the same contour as the cam track l6 shown in Fig. 3. Thus, the shaft 12, driven by the pinion 13 meshing with the gear segment 14 is caused to oscillate through 180. The reflector 24 is pivotally mounted 'ona pin 15 extending at right angles to the axis of rotation of shaft 12 and thus the reflector is caused to oscillatethrough 180.

Secured to the reflector adjacent to one end thereof is a pair of arms 16 and 11 which carry rollers 18 and 19'. A gear is rigidly mounted on' an'arm BI and the rollers 18 and19 are caused toLtravel' around the teeth jof gear 80. The

length of the arms 16 and 11 is so proportioned that, when the roller 18. is .between two teeth,

the roller "is at the outer end of a tooth. Thus,

j as the reflector is rotated about the center of. the 1 shaft, 12, the rollers 18 and 19 are caused to travel about the peripheryof gear 80, but in order .to be able to do so, they cause the reflector to oscillate about the pin 15 as one roller moves out ofthe space between two teeth and the other 'route, which coincides with the axis I3, he will observe the beam as a steady flash of light as it sweeps across him during its travel back and forth about the axis H. However, if he is oil to one side of the correct route, he will be struck by the edge of the flat beam and, inasmuch as the edge of the beam is continuously vibrating through the angle 6, the beam will appear to flicker as it passes him. Moreover, the further heis ofi the correct course the more apparent will be the flicker, inasmuch as the further away from the axis I3, the greater will be the linear movement of the edge of the beam which results from its oscillation through the angle 6.

In Figs. 18 and 19 there is illustrated an apparatus for producing a beam which rotates in a constant direction, but which is above the horizon a greater percentage of the time than it is below. Mounted on the shaft 85, which is driven at a constant speed, is an elliptical gear 86 which meshes with a similar elliptical gear 81 which is mounted for rotation on a fixed shaft 88 and is fixed to a circular gear 89. Gear 89 meshes with pinion 90, having one-half the number of teeth of the gear 89-, whereby'a gear ratio of two to one is obtained. Pinion 90 is mounted on a shaft 9| which carries the reflector 24.

The above described device operates as follows, Rotation of the shaft and the elliptical gear 86 at a constant speed causes the elliptical gear 81 to be-drlven at'a varying speed. In the position of the elliptical gears shown in Figs.'18

and 19, that is with the major axis of the gear 86 cooperating with the minor axis of the gear 81, the effect is that of a large geardriving a small gear, and therefore at this instant the gear 81 rotates at a higher speed than the gear 86. However, when the gear 86 has turned through its minor axis cooperates with the major axis'of the gear 81, and the elTect is that of a small gear driving a large gear and hence the gear 81 at this instant rotates at a slower speed than the gear 86. Between these two positions of the axes of the elliptical gears, the speed is continuously varying. It will thus be seen that for each revolution of the gear 81, it first travels faster than the gear 85, then slower, then faster again, and then slower. However, it is' desired'that the reflector 24 travel slowly through one-half of each revolution and rapidly through the other half. This is accomplished by providing a two to one gear ratio between the elliptical gear'81 and the shaft 9|. The gears are 30 arranged that the reflector 24 travels slowly during that half of its revolution in which the beam is above thehorizon and travels rapidly during the other half of its revolution when the beam is below the horizon and useless as a signal.

While I have shown several more or less specific embodiments of my invention, it is to be understood that this has been done for purposes of illustration only and that the scope of my invention is not to be limited thereby, but is to be determined by the appended claims when construed in the light of the prior art.

What'I claim is:

1. A beacon for signalling to aircraft, comprising light producing means, elongated projecting means adapted to produce a wide and relatively thin and flat beam of light. means for mounting said projecting means for rotation about a substantially horizontal axis of rotation substantially parallel to the longitudinal axis of said projecting means, means for repeatedly rotating said projecting means back and forth within an angular path about said axis of rotation, and means for regulating said rotation so that said projecting means may project said beam above the horizontal plane of said axis for a longer period of time than below said plane.

2. A beacon for signalling to aircraft, comprising light producing means, elongated projecting means adapted to produce a wide and relatively thin and flat beam of light, means for mounting said projecting means for rotation about an axis parallel to the length of said projecting means, means for repeatedly rotating said projecting means back and forth within an angular path about said axis, and means for regulating said rotation so that at least a portion of said path is above the horizontal plane extending through said axis.

3. A beacon for signalling to aircraft, comprising light producing means, elongated projecting means adapted to produce a wide and relatively thin and flat beam of light, means for mounting said projecting means for rotation about an axis parallel to the length of said projecting means, means for repeatedly rotating said projecting means back and forth through approximately 180 within an angular path about said axis, means for alternately rotating said projecting means back and forth through less than 180 within said path, and means for regulating said rotation so that at least a portion of said path is above the horizontal plane extending through said axis.

4. A beacon for signalling to aircraft at high altitudes, comprising light producing means, elongated projecting means adapted to produce a wide and relatively thin and flat fan-shaped beam of light, means for mounting said projecting means for rotation about a first horizontal axis substantially parallel to the length of said projecting means and about a second axis normal to said first axis, means for repeatedly rotating said projecting means back and forth in an angular path about said first axis, means for alternately rotating said projecting means about said second axis, and means for regulating said rotation so that at least a portion of said path may be maintained above the horizontal plane extending through said first axis.

ERIK ROBERT PARSBERG. 

